Metering mechanical tappet

ABSTRACT

A mechanical tappet utilizing a precision metering of oil from a reservoir to the pushrod seat through a disc on which the seat sits. The seat is permanently maintained in engagement with the disc by means of an O-ring held against the seat by a snap-in annular ring. Because of the resilience of the O-ring, it is possible for the seat to rotate with respect to the disc even though no axial separation is possible.

United States Patent [72] Inventors David L. Coates;

Ronald R. Erickson, both of Muskegon, Mich. [21] App1.No. 853,741 [22] Filed Aug. 28, 1969 [45} Patented Nov. 9, 1971 [73] Assignee Johnson Products, Inc.

Muskegon, Mich.

[54] METERING MECHANICAL TAPPET 6 Claims, 7 Drawing Figs.

[52] US. Cl 123/90.35, 123/90.48, 184/6 [51] Int.Cl F01m9/10, F01] 1/ 14 [50] Field of Search 123/90. 90.35, 90.51, 90.55, 90.57, 90.48; 184/6 '1. 6

[56] References Cited UNITED STATES PATENTS 2,797,673 7/1957 Black 123/90 2,948,270 8/1960 Bergmann 123/90 3,059,627 10/1962 Dadd 123/90 3,128,749 4/1964 Dadd 123/90 3,151,603 10/1964 Schumm 123/90 3,176,669 4/1965 KuchenetaL. 123/90 3,358,658 12/1967 Dadd 123/90 3,406,668 10/1968 Donnellyetal.... 123/90 3,450,228 6/1969 Wortmanetal. l84/6T Primary Examiner-Al Lawrence Smith Attorney-Price, Heneveld, Huizenga and Cooper ABSTRACT: A mechanical tappet utilizing a precision metering of oil from a reservoir to the pushrod seat through a disc on which the seat sits. The seat is permanently maintained in engagement with the disc by means of an O-ring held against the seat by a snap-in annular ring. Because of the resilience of the O-ring, it is possible for the seat to rotate with respect to the disc even though no axial separation is possible.

PATENTED NEW 91971 I 3,618,575

sum 2 or 2 6- INVENTOR W0 4. 00422.5 4940 42 ale/0.4M

METERING MECHANICAL TAPPET BACKGROUND OF THE INVENTION Although mechanical tappets do not require hydraulic fluid for their operation in contrast with hydraulic tappets, nevertheless oil must be supplied to the rocker arms for lubrication thereof. A conventional way of accomplishing this is by supplying the oil through the pushrod. Prior constructions so utilizing the pushrod have resulted in improper control of the flow of the oil through the pushrod. Attempts to meter the flow have been unable to overcome the problem of blockage due to foreign particles and at the same time not waste oil by having too little metering. An example of prior attempts at metering is U.S. Pat. No. 3,437,080 wherein the metering is accomplished by the tolerance of the fit of the pushrod seat within the tappet housing.

A very satisfactory metering device has been developed for use in hydraulic tappets and is disclosed in US. Pat. No. 3,358,658. However, prior to this time no one has thought of or been able to utilize the metering device of that patent in a mechanical tappet.

SUMMARY OF THE INVENTION The invention relates to a mechanical tappet utilizing precision metering of the type utilizing precision metering of the type heretofore available only in hydraulic tappets. Specifically, the invention provides an improved mechanical tappet operatively connected to a pushrod and comprising an oil reservoir, a pushrod seat, and means for metering oil from the reservoir through the seat and into the rod, the improvement comprising the metering means including a disc cooperatively engaged by a surface of the seat to meter oil flow and means for constantly biasing the surface against the disc to prevent separation such as caused by lash of the seat surface from the disc. We have found that such an improved tappet avoids the metering problems heretofore incurred by mechanical tappets.

Accordingly, it is an object of this invention to provide a mechanical tappet which utilizes precision metering of lubricating oil and at the same time avoids the tendency of blockage due to impurities in the oil.

It is another object of the invention to provide a tappet of the above character wherein the precision metering is accomplished even in the presence of lash.

It is a further object of the invention to provide a tappet of the above character which is inexpensive to manufacture.

Other objects and advantages will become apparent upon reference to the following drawings and detailed discussion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a fragmentary side-elevational view in section of a tappet constructed in accordance with the invention;

FIG. 2 is a plan view of the retainer utilized in FIG. 1;

FIG. 3 is a plan view taken along the line lIIlIl and showing the metering disc utilized in the invention;

FIG. 4 is a sectional view taken along the line IV-IV of FIG. I and showing only the pushrod seat;

FIG. 5 is a fragmentary view similar to FIG. I but illustrating an alternate embodiment of the invention;

FIG. 6 is a sectional view of the retainer ring illustrated in FIG. 5; and

FIG. 7 is a sectional view taken along the line VIIVII of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention relates to an improved mechanical tappet l0 utilized in a conventional engine block having a crankcase I1 and a passageway 12 connecting the tappet to an oil gallery. The tappet conventionally seats a pushrod 14 by means of a pushrod seat I6, the entire combination being reciprocated in a conventional fashion by a cam 18 on camshaft 20. The oil flows to the rocker arm through the pushrod 14 from the passageway 12 passing through a reservoir 22 defined by the body 24 of the tappet 10. the oil then flowing through the nonmetering holes 26 and thence through the metering valley 54 to a hole 28 in the bottom of the pushrod 14. The oil in the reservoir 22 is replenished each time the groove 30 of the housing 24 reciprocates past the opening to the passageway I2.

In accordance with the invention, we have discovered that it is possible to utilize as the metering means 40 and 54 the device disclosed in the aforesaid US. Pat. No. 3,358,658, which metering device utilizes a disc 40 which is preferably flat and has one or more holes 42 therein. The disc 40 is positioned upon annular shoulders 44 fonned by the housing 24 of the tappet and the pushrod seat is placed thereupon. The bottom surface 48 of the pushrod seat 16 cooperatively engages the disc 40 in the following manner. The engaging surface 48 is a land surface surrounding a hole 50 axially drilled through the pushrod seat, the land surface being formed by a valley or groove 52 concentrically positioned with respect to the hole 50. Still another groove or valley 54 is cut radially through the land surface 48 so that it extends from the hole 50 to the valley 52. It is by means of the metering valley 54 that oil which has moved into the valley 52 via the holes 42 in disc 40 is able to reach the hole 50 in the pushrod seat and thereby pass into the pushrod 14.

To allow this metering device to be utilized, it is necessary to insure that the pushrod seat 16 be biased at all times against the disc 40. To accomplish this, a resilient retainer 60 is pressed into the housing 24 so as to prevent the surface 48 of the pushrod seat from separating from the disc in the direction of reciprocation of the tappet. That is, any tendency to separate will be caused by lash, and this tendency is prevented by the use of the retainer 60 comprising a flexible O-ring 62 such as can be formed from a nitrile rubber or other materials resistant to oils and temperature, the O-ring 62 in turn being restrained by an annular ring 64 snapped into place within a groove 65 in the housing 24. The annular ring 64 comprises a disc the outer portion of which is bent upward to form shoulder 66. To reduce the amount of the ring 64 which must flex into place in the groove 65, two portions of the outer diameter of the ring as measured by two parallel cords 68 are excluded from the ring when the ring is stamped out of sheet metal.

Because of the resiliency of the O-ring 62, it is still possible for the pushrod seat 16 to rotate with respect to the disc 40 even though no axial separation is possible. This rotation facilitates in maintaining the land surface 48 free of impurities which would otherwise tend to tip the disc 40 in its orientation with respect to the pushrod seat or clog the valley 54.

FIGS. 5 and 6 illustrate an alternate embodiment of the invention wherein the O-ring has been eliminated. Similar parts which correspond to those utilized in the previous embodiment utilize the same numerals to which the distinguishing suffix a" has been added. Thus, as shown in FIG. 5, a tappet 10a is operated by a cam 18a within a crankcase 11a, the oil flowing from a passageway 12a through a reservoir 22a, metering means 40a and 54a and up into a pushrod 14a. The metering means 40a and 540 are identical in all respects with that described in the previous embodiment. To hold the metering means 40a and 54a in the proper relationship so that the pushrod seat has its land surface in constant engagement with the disc, an annular ring 60a is press-fit into engagement with the internal diameter of the end 70 of the tappet 10a. To insure that the annular ring will be press-fit against movement in the direction of reciprocation of the tappet, the upper portion 74 of the annular ring 60a includes a radial extension which produces an external diameter that exceeds the internal diameter of the end 70. The remaining cylindrical portion 76 of the ring 60a has a diameter which is less than that of the end 70.

As in the earlier embodiment, the annular ring prevents the pushrod seat from axially separating from the disc as would otherwise occur in the event that lash develops in the pushrod 14a. Thus, precision metering is maintained in the tappet.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

1. In a mechanical tappet operatively connected to a pushrod and comprising an oil reservoir defined by a tappet housing, a pushrod seat, and means for metering oil from said reservoir through said seat and into the rod; the improvement comprising said metering means including a disc cooperatively engaged by a surface of said seat to meter oil flow. and means for constantly biasing said surface against said disc to prevent separation such as caused by lash of said seat surface from said disc; said biasing means including a resilient retainer, which, while permitting rotation of said seat with respect to said reservoir, prevents said surface from separating from said disc in the direction of reciprocation of said tappet; and said retainer including a resilient member and a generally annular ring restrained from movement in said reciprocating direction by said housing, said annular ring pressing said resilient member against said seat.

2. The improved tappet as defined in claim 1, wherein said annular ring has a portion of its external diameter removed along parallel chords.

3. The improved tappet as defined in claim 2, wherein said disc is positioned between said seat and said reservoir, said seat has a hole therein along its axis, and said surface comprises a land surface surrounded by valleys, one of which extends radially from said hole to another of said valleys.

4. In a mechanical tappet operatively connected to a pushrod and comprising an oil reservoir defined by a tappet housing, a pushrod seat and means for metering oil from said reservoir through said seat and into the rod; the improvement comprising said metering means including a disc cooperatively engaged by a surface of said seat to meter oil flow, and means for constantly biasing said surface against said disc to prevent separation such as caused by lash of said seat surface from said disc; said biasing means including a resilient retainer, which, while permitting rotation of said seat with respect to said reservoir, prevents said surface from separating from said disc in the direction of reciprocation of said tappet; and said retainer including an O-ring and a generally annular ring restrained from movement in said reciprocating direction by said housing, said annular ring pressing said O-ring against said seat.

5. The improved tappet as defined in claim 4, wherein said annular ring has a portion of its external diameter removed along parallel chords.

6. The improved tappet as defined in claim 5, wherein said disc is positioned between said seat and said reservoir, said seat has a hole therein along its axis, and said surface comprises a land surface surrounded by valleys, one of which extends radially from said hole to another of said valleys. 

1. In a mechanical tappet operatively connected to a pushrod and comprising an oil reservoir defined by a tappet housing, a pushrod seat, and means for metering oil from said reservoir through said seat and into the rod; the improvement comprising said metering means including a disc cooperatively engaged by a surface of said seat to meter oil flow, and means for constantly biasing said surface against said disc to prevent separation such as caused by lash of said seat surface from said disc; said biasing means including a resilient retainer, which, while permitting rotation of said seat with respect to said reservoir, prevents said surface from separating from said disc in the direction of reciprocation of said tappet; and said retainer including a resilient member and a generally annular ring restrained from movement in said reciprocating direction by said housing, said annular ring pressing said resilient member against said seat.
 2. The improved tappet as defined in claim 1, wherein said annular ring has a portion of its external diameter removed along parallel chords.
 3. The improved tappet as defined in claim 2, wherein said disc is positioned between said seat and said reservoir, said seat has a hole therein along its axis, and said surface comprises a land surface surrounded by valleys, one of which extends radially from said hole to another of said valleys.
 4. In a mechanical tappet operatively connected to a pushrod and comprising an oil reservoir defined by a tappet housing, a pushrod seat and means for metering oil from said reservoir through said seat and into the rod; the improvement comprising said metering means including a disc cooperatively engaged by a surface of said seat to meter oil flow, and means for constantly biasing said surface against said disc to prevent separation such as caused by lash of said seat surface from said disc; said biasing means including a resilient retainer, which, while permitting rotation of said seat with respect to said reservoir, prevents said surface from separating from said disc in the direction of reciprocation of said tappet; and said retainer including an O-ring and a generally annular ring restrained from movement in said reciprocating direction by said housing, said annular ring pressing said O-ring against said seat.
 5. The improved tappet as defined in claim 4, wherein said annular ring has a portion of its external diameter removed along parallel chords.
 6. The improved tappet as defined in claim 5, wherein said disc is positioned between said seaT and said reservoir, said seat has a hole therein along its axis, and said surface comprises a land surface surrounded by valleys, one of which extends radially from said hole to another of said valleys. 